JPS61268772A - Coating composition for preventing corrosion - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides compositions suitable for the production of surface protective coating compositions, which prevent corrosion of metal surfaces, especially ferrous metal surfaces, by mixing with a binder.

The present invention relates to coating compositions so produced and articles or structures having ferrous metal surfaces coated with such compositions.

It is well known that metal surfaces can be protected from corrosion by placing the metal surface in electrical contact with a second metal of lower standard electrode potential (ie, a galvanically protective metal). A common pear of this form of protection is galvanized steel sheet.

It is also known to utilize galvanically protective metal particles, usually finely divided particles, in paints.

In particular, it is known to protect steel surfaces using paints containing zinc dust. Known zinc-containing binders can include organic or inorganic binders, such as epoxy resins or ethyl silicate. The zinc content of such paints is generally 70-95% by weight and therefore the paints are zinc rich.
-rich) paint.

Zinc-rich paints provide very good corrosion protection to steel surfaces. However, upon exposure to the environment, a layer of white zinc corrosion products forms relatively quickly on its surface. These corrosion deposits are not visible to the naked eye and make additional coatings difficult. Even when topcoats of other paints are applied to zinc-rich paints before exposure to the environment, zinc corrosion can cause intercoat adhesion problems;
Also, white zinc corrosion may form on the surface.

A problem associated with zinc corrosion in zinc-rich coating compositions is that an effective amount of inorganic oxide particles in which corrosion-inhibiting ions are chemically bonded to the surface of the inorganic oxide particles by ion exchange is incorporated into said compositions. It was found that by letting people talk to each other, it was possible to reduce the problem.

According to one aspect of the invention, compositions suitable for making surface protective coating compositions by mixing with a binder include: (1) elemental zinc in particulate form; (ii) corrosion protection by ion exchange; Includes inorganic oxide particles to which cations are chemically bonded.

- The ratio of elemental zinc to ion-exchanged inorganic acid is preferably 75:1 to 6:1 by weight.

Other aspects of the invention include: (i) a binder; (ii) 50% based on the weight of the coating composition;
~90% by weight of elemental zinc in particulate form, and (IL)
A composition suitable for application to metal surfaces to prevent corrosion is comprised of an effective amount of inorganic oxide particles having corrosion inhibiting ions chemically bound to the surface by ion exchange.

The amount of binder is 1 based on the weight of the coating composition.
A range of 0 to 601%, preferably 15 to 35% by weight is advantageous.

Inorganic oxide particles, in which corrosion-inhibiting ions are bound to the surface of the inorganic oxide by ion exchange, are known as corrosion inhibitors and are disclosed in British Patent No. 2071070B, European Patent Application No. WC46057 and European Patent Application No. 8981
It is disclosed in No. 0. UK Patent Application No. 2091235
No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, 2003, 2003, discloses a method for making certain corrosion inhibitors of this type. The disclosures of these patent applications should be incorporated herein by reference.

Any of the ion-exchanged inorganic oxide particles disclosed in these patents and patent applications can be used in the present invention. However, preferred particles are those in which the ions bound to the inorganic oxide are cations, and the preferred inorganic oxide is silica.

Particularly preferred for use in the present invention are corrosion inhibitors comprising silica particles in which calcium ions are chemically bonded to the silica particles by ion exchange. Preferably, the inorganic oxide particles have a particle size of less than 40μ, more preferably less than 25μ.

Advantageously, the inorganic oxide is enriched with up to 2.5 mmol/g of corrosion-inhibiting ions. The lower limit is about 0.01 mmol/g, preferably 0605 mmol/9
It is.

Typically, the total amount of elemental zinc and ion-exchanged inorganic oxides contained in the coating composition is 60-95 wt%. The volume ratio of zinc:ion 9:converted inorganic oxide is, for example, 1:0.05 to 1:1.2, preferably 1:0.67 to 1:1, and on a weight basis 75. The ratio is 21 to 3:1.

The coating compositions of the present invention are typically enriched with binders for zinc and inorganic oxides, especially film-forming polymers that are organic polymers or resin binders.

Examples of organic binders include epoxy resins, epoxy esters, chlorinated polymers and polystyrene. Inorganic binders are rich in silicates (both organic and inorganic).

Coating compositions are in the form of paints, which the inventors may refer to as enamels, lacquers, varnishes, basecoats, primers, seals, eye creams, stoppers, and the like.

A saponifying agent may also be mentioned in the coating composition.

The coating composition can also be enriched with additives conventionally used in paints, such as pigments, driers, thickeners and antiskinning agents.

The coating composition is manufactured by conventional methods, and
Applicable.

The present invention also includes structures having ferrous metal surfaces that have been provided with a coating according to the present invention.

The invention is illustrated by the following examples.

Example 1 Preparation of Calcium-Exchanged Silica Calcium hydroxide was slowly added to a stirred slurry of silica in water (2 parts water to 1 part silica) at about 20°C.

- is no longer higher than 10. - Once stabilized, filter the calcium-exchanged silica, wash with water,
Kneaded underwater. The product was then dried on trays in an oven. X-ray fluorescence analysis of the product showed 6.6% by weight of calcium (1.65 mmol/i). The average particle size was 7.1μ.

Production of paint All other components except the desiccant and about 1/3 of the resin are mixed in a ball mill for 20 hours, and then the remaining resin and desiccant are mixed to produce the composition shown in Table 1. A zinc-rich paint according to the invention was prepared having:

For comparison, a similar zinc-rich paint not according to the invention was prepared without calcium-exchanged silica. This comparative composition is also shown in Table @1.

Table Wc1 - Painted Composition "Synolac J" (synolac) is a registered trademark.

Refers to the total solid content excluding tatami epoxy ester resin.

and the volumetric concentration in the dry film.

Bentone 64 is a commercially available organically modified montmorillonite clay sold by NL Industries, Inc., and is used as a lubrication agent and rheology modifier. Benton is a registered trademark.

Corrosion Testing The paint composition was applied to degreased, polished mild steel panels by plush coating and allowed to dry. The dry film thickness of the paint was 85-105 microns.

The coating was scratched to reveal bare steel and the panels were subjected to AaTM method B 117-73 salt spray testing. After 24 hours of exposure to salt spray, the panels coated with the comparative composition developed white zinc corrosion deposits on their entire surface, whereas the panels coated with the composition according to the invention were free of such corrosion products. Ta. After 550 hours of exposure to salt spray, panels coated with the comparative composition had relatively large amounts of white zinc corrosion deposits on the surface, the coating blistered, and corrosion of the metal was significant. The panels coated with the paint according to the invention showed very little white zinc corrosion deposits on its surface after 350 hours. There was no blistering in the paint film and no signs of corrosion on the mild steel.

These results show that by use of the present invention: (+) white zinc corrosion deposits on surfaces are significantly reduced, and (ii) corrosion of steel is also reduced.

Example 2 Preparation of Calcium-Exchanged Silica Calcium-exchanged silica was prepared as described in Example IK, except that the filter cake was dried in an oven and pulverized after drying to an average particle size of 4.3μ.

X-ray fluorescence analysis of the product revealed 6.1 wt% (1,5
5 mmolf g) of calcium am was shown.

Preparation of Paints Five sink-rich paint compositions according to the present invention containing different concentrations of calcium-exchanged silica corrosion-inhibiting particles were prepared. The compositions of these five paints as well as two comparative compositions are shown in Table 2.

Composition B is a typical sink-rich epoxy coating composition of the type commonly used on new steel structures.

Composition C is an experimental composition to determine whether the addition of a zinc phosphate corrosion inhibitor to Composition B improves performance.

Chickenmen is a hydrogenated castor oil that acts as a chickentrope. Persamide 115 is a polyamide resin. Beetle BK640 is an n-detylated urea resin and is used as a flow control agent.

Part A of each composition was prepared by mixing the resin, solvent, and chickentrope, heating at about 35° C. for about 10 minutes, and then using a high speed disperser to disperse the pigment into the dispersed mixture.

Corrosion Test Parts A and 3 were mixed and then applied to standard degreased and polished mild steel panels. The paints were applied by Spin coating, except for Comparative Composition C, which was applied by brush. Scratch the coating until bare metal is exposed and then attach the panel to ABTM method B117-7.
The salt spray test was carried out for 500 hours. AEI measures the amount of white zinc corrosion deposits on the panel surface and the amount of corrosion under the steel coating.
The coating was evaluated by TM method D610-68, and the degree of blistering of the coating was evaluated by ABTM method D714-56. Evaluation test ABTM method D610-68 and ASTM
Method D714-56 is a visual test with values between 0 and 100.
Shown on a scale, 10 indicates a good result, ie, no corrosion or blisters, and 0 indicates a bad result, ie, 100 parts of the surface are corroded or very large blisters.

The results are shown in Table 1, Part 3, and show that the paint according to the invention protects mild steel panels better than either of the two comparative compositions. The appearance of zinc corrosion deposits is reduced compared to comparative compositions and the paints according to the invention are less prone to blistering.

Somewhat surprisingly, the best results were obtained with a paint in which the 45 vol tS zinc dust was replaced with calcium-exchanged silica corrosion protection particles (Example 6).

Table 3 The above results are on an exponential scale.

Example 7 and Comparative Examples 8 and 9 For comparison purposes, zinc-rich paints based on epoxy resins formulated with barium metaborate at two levels of substitution (10% by volume and 20% by volume) Same composition as 2)
was prepared and tested against a zinc rich paint containing 45 volumes of zinc substituted with calcium/silica as in Example 2.

The formulation is shown in Table 6, and the results of the ASTM method salt test after 800 hours are shown in Table 4.

Results with zinc metaborate (recommended by the manufacturer for this application) showed poor performance, and much better performance was obtained from monocalcium/silica at high levels of substitution.

Comparative Example 110 and Examples 11 and 12 Calcium/
Thin Rich paints based on chlorinated rubber binders were prepared by incorporating silica (same as the pigment in Example 2) and tested against Thin Rich paints without additives. The formulations are shown in Table 7, and the results after 350 hours of ASTM salt spraying and sweet salt spraying are shown in Table 5. The results show a significant increase in performance with increasing calcium/silica content, but the performance was inferior to epoxy-based paints due to the poor performance of the epoxy binder.

Table 6 Dathan 11-Ml Ke1, Buckman Laboratories Engineering nc
, ) is a barium metaborate pigment.

BFKA-651='! , Kurokununa 7F Gully (a
Wet line Tlcll supplied by Roxon and Garry) Inc. ! It is a 1ull agent.

Paints 8 and 9 were made as in Example 2; Paint 7 was made by ball milling Part A with all components except the zinc dust, which was later added to a high speed disperser.

In the case of flattening, parts A and B were mixed immediately before application.

In the case of No. 7 Omotei Pete, all components other than the pigment were dissolved in a solvent before blending the pigment. In Paint 10, the zinc dust was compounded in a high speed disperser; in Paints 11 and 12, the pigment was compounded in a tar mill.

Alloprene (A11 oprθne) R10 is a chlorinated male resin supplied by Ko-C Kosha.

Aelealor 70 is a chlorinated paraffin resin enriched as an inert filler supplied by Ko-C Kosha.

Celechlor 42 is a chlorinated paraffin enriched as a plasticizer supplied by Ko-C Kosha.

Leoplas 59 is a stabilizer (epoxidized soybean oil) supplied by Ciba-Geig7.

Claims (10)

[Claims] (1) a binder characterized in that it contains (i) elemental zinc in particulate form; (n) inorganic oxide particles to the surface of which corrosion-inhibiting cations are chemically bonded by ion exchange; A composition suitable for producing a surface protective coating composition by mixing. 2. The composition of claim 1, wherein the amount of elemental zinc:ion-exchanged inorganic oxide is from 75:1 to 3:1 by weight. (3) The composition according to claim 1 or 2, wherein the inorganic oxide is silica and the corrosion-inhibiting ion is calcium ion. (4) (i) binder; (ii) 50 to 50, based on the weight of the coating composition;
90% by weight of elemental zinc in particulate form, and (iii)
A coating composition suitable for application to metal surfaces for corrosion protection, characterized in that it consists of an effective amount of inorganic oxide particles, to the surface of which corrosion-inhibiting ions are chemically bound by ion exchange. (5) The coating composition according to claim 4, wherein the weight ratio of elemental zinc to ion-exchanged inorganic oxide is from 75:1 to 3:1. (6) The coating composition according to claim 4 or 5, wherein the inorganic oxide is silica and the corrosion-inhibiting ion is a calcium cation. (7) The amount of corrosion-preventing ions bonded to the surface of the inorganic oxide is 0.01 to 2.5 per 1 g of the inorganic oxide.
Claim 4, which is millimoles of corrosion-inhibiting ions.
The coating composition according to any one of Items 1 to 6. (8) A two-component pack further comprising a curable resin and a curing agent for the curable resin, the curable resin and the curing agent being in different parts of the pack, and by mixing the A two-component pack, characterized in that it forms the coating composition according to any one of items 4 to 7. (9) (i) a binder; (ii) 50-90% by weight of elemental zinc in particulate form; and (iii) an effective amount as a corrosion inhibitor, with calcium cations chemically bonded to the surface by ion exchange. A paint suitable for application to metal surfaces to prevent corrosion, characterized in that it consists of silica particles. (10) A ferrous metal structure coated with the composition according to any one of claims 4 to 7 or 9.